This invention relates to the field of copolymers of styrene and maleic anhydride (SMA) and to methods of preparation of SMA derivatives, methods of use, and compositions prepared from SMA.
Saturated carboxylic acid salts of imidized SMA copolymers were previously suggested for cationic polymerization systems. For example, Pratt, U.S. Pat. No. 3,941,808, disclosed SMA copolymers having pendant tertiary amine groups containing a salt-forming tertiary nitrogen atom neutralized to the extent of at least 75% with saturated mono-carboxylic acids having at least eight carbon atoms such as stearic, lauric, or behenic acid to form salts which lower the surface tension at oil-water interfaces. Dehm et al., U.S. Pat. No. 4,618,655, disclosed polymers containing styrene moieties and cyclic imide moieties reacted with saturated anhydrides. However, no one had previously suggested ethylenically unsaturated imidized SMA salts which are curable, promote cure speed, function as dispersants of pigments and fillers, as emulsifying agents, and are especially useful in radiation cure applications where they improve cure speed, hardness, and adhesion properties of polymer compositions.